Polymers containing repeated disulfide bonds have received a great deal of attention due to dynamic covalent bonds that are easily broken and formed again (E. K. Bang et al. Chem. Sci., 2012, 3:17521763; E. Q. Rosenthal et al. Biomacro-molecules, 2012, 13, 154-164; Y. Q. Lv et al. Analyst, 2012, 137, 4114-4118.1-3). The application of poly(disulfide)s include industrial plastics, medical materials, and catalysts. Organic solvents are frequently used in the production of fine chemicals, petrochemical products, and medicines (Y. Z. Meng et al. Polymer, 2005, 46:11117-11124; M. Ou et al. Biomaterials, 2009, 30:5804-5814; B. J. Sparks et al. Chem. Mater., 2012, 24:3633-3642; Z. Z. Zhang et al. Chem. Sci., 2011, 2:1826-1830).
Wastewaters discharged from reactors in industries contain heavy concentration of organic solvents that are mixed in water. Thus, the development of effective and low-cost technology for removing toxic solvents from wastewater is crucial in technical and environmental terms. Removal of organic pollutants from wastewater has been widely studied through physical, chemical and biological technologies (V. K. Gupta et al. RSC Adv., 2012, 2:6380-6388; Z. Y. Xu et al. Crit. Rev. Environ. Sci. Technol., 2003, 33:363-389; J. Theron et al. Crit. Rev. Microbiol., 2008, 34:43-69.8-10).
Some materials such as activated carbon, porous silica, zeolites, organic clays, metal organic frameworks and membranes have been studied to remove toxic organic compounds from wastewater (V. K. Gupta et al. RSC Adv., 2012, 2:6380-6388; M. M. Khin et al. Energy Environ. Sci., 2012, 5:80758109; H. A. Patel et al. Ind. Eng. Chem. Res., 2009, 48:10511058; D. V. Patil et al. Ind. Eng. Chem. Res., 2011, 50:1051610524; B. J. Pan et al. Chem. Eng. J., 2009, 151:1929; S. Debnath et al. Chem. Eur. J., 2008, 14:6870-6881; Y. L. Zhang et al. J. Mater. Chem., 2010, 20:4609-4614). Biological decomposition of organic pollutants in aqueous solutions or wastewater is also a promising method of a sustainable and environmentally friendly industry (S. Mahendra et al. Chemosphere, 2013, 91:88-92).
In several recent years, as the development of polymer materials with functionalities and controllable pore geometries has been of increasing interest, the range of application thereof has been expanded (H. A. Patel et al. J. Mater. Chem., 2012, 22:8431-8437; H. A. Patel. et al. Chem. Commun. 2012, 48:9989-9991).
Polymers and their derivatives, including poly(acrylic acid), cellulose, poly(ortho-carbonate) as a carbon-containing material, microcrystalline polymers, and poly(lactic acid), have been studied as highly absorbent materials for removing oils and organic solvents from water (T. Ono et al. Adv. Funct. Mate 2008, 18:3936-3940; G. Marci et al. Green Chem., 2006, 8:439-444; Z. L. Fan et al. ChemPlus Chem, 2013, 78:1282-1287; X. C. Gui et al. Adv. Mater., 2010, 22:617-621; H. B. Sonmez et al. Macromolecules, 2005, 38:1623-1626; A. Li Et al. Energy Environ. Sci., 2011, 4:2062-2065; Z. X. Xue et al. RSC Adv., 2013, 3:23432-23437). Such materials have a disadvantage in that they are synthesized using expensive catalysts and monomers only at high temperatures, and also entail a problem in that they cannot remove highly concentrated solvents mixed with aqueous solutions.
Thus, there is a need for the development of polymer materials that are recyclable under catalyst-free mild conditions with ability to effectively absorb only organic solvents in aqueous solutions or wastewater.
Accordingly, the present inventors have prepared a disulfide-linked covalent organic polymer from a monomer having a terminal thiol group (—S—H), and found that the prepared organic polymer can selectively absorb only organic solvents on aqueous solutions or wastewater, thereby completing the present invention.